Apparatus for heating and cracking oil



Patented Feb. 16, 1932 UNITED STATES PATENT OFFICE JOHN C. BLACK, OF LOS ANGELES,` AND EARLE W. GARD, 0F PALOS VERDES ESTATES,

CALIFORNIA i APPARATUS FOR HEATING AND GRACKING OIL 'Original application tiled November 16, 1926, Serial No. 148,735. Divided and this application led February 5, 1929.

This invention pertains to an apparatus for cracking oil, especially for cracking oil in a liquid phase and is a division of the pending application of John C. Black and Earle W. Gard, Serial No. 148,735, filed November' 16, 1926 for method and apparatus for heating and cracking oil. This invention is more particularly directed to an apparatus for crackingr oil where an oil is raised to the cracking temperature and then maintained at substantially said cracking temperature, or at a higher temperature for a prolonged period of time, while maintained under a pressure sufficient to prevent any substantial vaporization. It is an object of this invention to devise an apparatus by which the oil may be maintained at this cracking temperature, or at a higher temperature, for any predetermined length of time to obtain any desired amount of cracking.

W'e have found that it is particularly difficult to maintain an oil at any given temperature in ordinary furnace construction. In passing oil through coils heated by combustion gases there is a tendency for the oil to fluctuate in temperature during its passage through the tubes due to radiation and inequalities in the heating. Another danger in heating the oil at the cracking temperature is overheating, with consequent carbonization and gasification. It is therefore an object of our invention to devise an apparatus for heating oil wherein the oil may be raised to a cracking temperature and maintained at substantially said cracking temperature during passage through the coils in a furnace, wherein the tendency for superheating the oil is minimized or completely eliminated, and the temperature of the oil maintained substantially constant during its passage through the coils. Another object of our invention is to devise an apparatus for cracking oil wherein the heat economy and heat distribution is at a maximum, and in which 'the capacity, that is, the volume of oil which may be treated for any given furnace volume, is at a maximum. Another object of our invention is to devise an apparatus wherein repairs or replacement of tubes is made easy, and is facilitated. Further objects of our Serial No. 337,682.

invention will appear from the following description and particularly by reference tothe accompanying drawings which illustrate our invention. i

In said drawings, Figure 1 is a sectional View of an elevation of the front end of a furnace.` Figure 2 is a side elevation of one of the vertical banks of the furnace. Figure 3 is a plan view of said vertical bank. Figure 4 is a right side view of Figure 2, and Figure 5 is a left side view of Figure 2.

In Figure 1, l is a setting of the furnace. 2 is the firewall separating the furnace into two sections, creating in fact two separate furnaces. 3 are the arches for the furnace. 4 is the fire-box of a Dutch oven, and 5 is the Dutch oven arch. 6 is the front wall of the furnace. On said wall is an H beam, 7, supported on plates 8 in the side wall of the setting. On this H beam is set a removable I beam 9. Supported on said I beam 9 are a plurality of removable channels 10 and 11. These channels arepierced with holes through which the tubes 12 pass loosely. The channel 10 contains one single row of tubes crossconnected between the furnaces as shown. The channels 11 each contain two rows of tubes which are connected to analogous rows in the other furnaces shown. The course of the oil through these tubes is as shown, first into the bottom row or pass of the left-hand furnace across to the bottom rowor pass of the right-hand furnace, up to the row immediately above in the right-hand furnace, across to the row immediately above in the left-hand furnace, and up through the next three rows in analogous manner as indicated.

The tubes are all welded together. On cutting the cross-connections from one channel section to the channel section immediately above and the cross connection between furnaces, each channel section may be separately removed. This removal is facilitated by the I beam space 9. i Thus by supporting the channels 10 and 11 by means of a sling caught around the tubes 12 in said section, and around the tubes in section 15 or around some outside support, the beam 9 may be removed. The channel 10 may then be dropped and removed without interference partially cracked, it is removed region o f'hot combustion gasesyto a cooler combustion gases.

furnace.

13 is an H beam set in the setting of the Vfurnace and supported on plates 14. On this H beam are set a plurality of vertical banks of coils 15. Each of these sections is composed of a sinusoidal header as shown in 'Figures 1, 4 and 5. Theheader 16 is a cast I beam section as shown in Figure 3. This header is pierced by a plurality of staggered holes through which tubes 17 pass. The course of the oilin tubes through each header is such as to move upward zigzag across the header, across the top of the header and down zigzag on the other side of the header as shown. There is a slight space between the headers as indicated on Figure 1 so that each header may be easily removed.

The course of the oil from the lower coils is asshown on Figure 1, upward through the right-hand pass of the coils in the'bank, across and downward through the left-hand pass of the bank, across to the next vertical pass in the Y adjoining bank, upward through the right-hand pass, downward through the lefthand pass in an analogous manner upward and downward through the adjoining head- V'ers or banks in the furnace, then passes out from said furnace across a connection to the upward pass of the right-hand bank in the adjoining furnace, and upward and downward through the various vertical banks in the right-hand furnace, then out from the bottom of the left-hand pass in the left-hand section.

These coils are welded. Each bank or'section is composed of a series of tubes in staggered relation, each tube containing a deadend 2O and a block 22. There is a cross connection 21 welded between the tubes so as to Y provide this dead-end. The purpose of said dead-end is to allow the use of a block for cleaning out the individual tubes.

The operation of the furnace is as follows: The oil is introduced into the lower banks of coil in channel 10, and is raised during its passage through the tubes 12 in channels 10 and 11 so that it reaches the cracking point at the exit from the upper horizontal pass. The course of the oil is concurrent with the combustion gases as shown. The purpose of the concurrent passage is to prevent the oil, as it reaches the cracking temperature, which has received an incipient cracking, from coming in contact with the hot combustion gases entering the furnace from the Dutch oven. Were this allowed, these hot gases `might vcause a superheating of the oil with consequent carbonization and gasification. By passing'the oil concurrently with the combustion gases, as the oil is heated up and from the region of Voil enters.

The oil is then passed to the reaction coils 17 where the oil is maintained at the cracking temperature. It will be seen that by passing the oil concurrently with the combustion gases, and by placing the oil at or near its cracking temperature in the proximity of thereaction coils, any cooling down of the reaction coils is prevented. This cooling would'be `obtaine'dwere-the cold oil passed in through the upper horizontal coils and passed counter-.current with combustion gases. This cool oil would tend to cool down the reaction coils and cause a fluctuation in the temperature of the oil passing through the reaction coils 17.

By passing the oil from one horizontal coil in one furnace to the analogous horizontal coil in the other furnace, and back and forth in this manner as' shown, an equalization in the load on both furnaces is obtained andtheir simultaneous `control is therefore facilitated. This would be'equivalent to a single furnace of double the width. By spreading the coils in width, the vertical heightof kthe Vcoil is diminished and the concentration of the fire diminished, thus reducing the blasting effect of the flames.

The oil, as shown, passes up from the preheating coils 12 tothe cracking coils. The oil comes into the lower coils in the left-hand furnace, leaves the preheating coils in -the right-hand furnace, enters the reaction coils in the right-hand furnace -and leaves-thereaction coils in the left-hand furnace, that is, in the same furnace as that to whichY the cold As will be apparent, the major amount Vof heating occurs in thelowest bank of coils, that is, in the coils in channel 10 Ain the :left-hand furnace. The major amount of cracking occurs in coil 17 in the right-hand furnace, and the minor amount of cracking occurs in the coils in the left-hand furnace. There is, therefore, an equalization of'load on eachfurnace. A

The lowest bank lof coils in the furnaces re- -ceives the major amount of heating, and

therefore `are easier to Aburn-out. They are placed in single paths so that their removal is facilitated,as described above.Y By staggering the tubes in the furnace the channeling of the gases is prevented and a complete envelopment of the tubes and distribution ofthe gases throughout the furnace is made lpossible.

vAnother Yadvantage Iof the staggering is that it permits the replacement of worn tubes by new tubes. Thetubes,` because of the heat, are caused to sag considerably, and thissagging is so marked that if any tu'bel in any ofthe intermediate banks was vremovedand a new tube introduced, the introduction -of this tube would be linterfered with by the rsagging of the upper tubes. By staggering the tubes as shown, a new straight tube maybe introduced withoutinterference -by the' sagging of the upper tubes, since the distance between the center of the tubes is greater than that which would be obtained by lacing the tubes inthe same planes, or immediately over each ot-her.

The sinusoidal form of the headers 16 permits the placing of a greater number of tubes in the same volume of furnace space. The unit construction of the banks permits the same ease of replacement of tubes as that obtained in the unitconstruction of the lower tubes, for if one tube -should need repairing the whole bank may be removed easily and a new bank slipped into place immediately and the tubes replaced or repaired when convenient without interrupting the operation of the furnace for an undue length of time.. Another advantage of the use of vertical banks is that the removal of one bank is not interfered with by the sagging of the tubes, as is the case of coils 12 where the units were placed horizontally.

The construction of the reaction coil or cracking coil 17 permits the equalization of temperature throughout the co1l, and therefore enables the oil to be maintained at a substantially const-ant temperature throughout its passage through the coils. By passing the oil upward in single passes from the hottest to the coldest zone of the furnace, any accidental over heating of the oils is minimized by the fact that it is immediately removed from the hotter zone to the cooler zone. By immediately returning the oil from this single upward pass downward through :mother single pass to the hotter zone of the furnace, any accidental cooling of the oil below the desired cracking tem erature is immediately neutralized by the fact that it passes into the hotter zone of the furnace, Each downward pass as will be seen, is between two upward passes so that there 1s an equalization of temperature between the upward and the downward passes, aiding in the maintainment of aconstant temperature throughout the coils. By maintaining this constant temperature a constant reaction is obtained throughout the coil resulting in a better control and a higher yield than if the temperature were allowed to fluctuate. over any substantially wide limits. By splitting the coils between two furnaces a more eXact control of the heating of the several coils is obtained, and also a support is obtained for the supporting beams.

The above is not to be taken as limiting our invention, but merely as illustrative of the best manner of carrying out our invention.

lVhat we claim is:

1. Apparatus for cracking oil, comprising, a plurality of furnaces, a coil situated in the hottest part of said furnaces, said coil consisting of a plurality of sets of horizontally connected tubes, the tubes of each set stag- "gered inrrelation to thetubes ofthe `set below it, and the sets of tubes `connected each vto each man `upward or concurrent direction `with the flowy of furnace gases,`a removable supportfor `the zcoil to facilitate the'wthdrawal of any set of tubes, channel headers tohold the tubes in place, means for passing nally right and left to the tube above andheld` in place` by `sinuous channel headers, each tube iin fthesets of tubes staggered in relation to the tube above it, the sets of tubes connected each to each so that the flow of oil in the tubes is alternately concurrent or upward, and countercurrent or downward with the flow of furnace gases a third coil situated in the upper or cooler section of another of said furnaces connected to the second coil, and of similar construction to the second mentioned coil, and having an outlet for the oil.

2. Apparatus for cracking oil, comprising, two furnaces, a coil situated in the hottest part of said furnaces, said coil consisting of a plurality of sets of horizontally connected tubes, the tubes of each set staggered in relation to the tubes of the set below it, a removable support to support the coil and to facilitate the withdrawal of any set of tubes, the` sets of tubes connected each to each in an upward or concurrent direction with the flow of furnace gases, channel headers to hold the sets of tubes in place, means for passing oil into the lowest or hottest set of tubes in said coil; another coil situated in the upper or cooler section of each of the said furnaces, one of which is connected to the topmost set of tubes of the first mentioned coil, said second mentioned coils consisting of a plurality of sets of horizontally positioned tubes, the tubes of each set connected to each other alternately diagonally right and left and held in place by sinuous channel headers, each tube in the sets of tubes staggered in relation to the tube above it, and the sets of tubes connected each to each so that the flow of oil in the tubes is alternately concurrent or upward, and countercurrent or downward, with the flow of furnace gases.

3. Apparatus for cracking oil comprising, a plurality of furnaces, a coil situated in the lower' sections of said furnaces, consisting of a plurality of sets of horizontally connected tubes, theI tubes of each set staggered in relation to the tubes in the set above and below it, the sets of tubes connected each to each; a removable support for the coil, channel headers to hold the tubes in place, means for passing oil into the lowest set of tubes in said coil; a second coil situated in the upper section of each of said furnaces, connected to the topmost set of tubes in the rst-mentioned coil, consisting of a plurality of sets of horizontally positioned tubes, the tubes of each set connected alternately, diagonally right and left to the tubes above and below it, held in place by sinuous channel headers, the sets of tubes connected each to each so that the low of oil in the tubes is alternately concurrent or upward, and countercurrent or downward with the flow of furnace gases; means for withdrawing oil from the second coil.

In testimony whereof we afix our signatures.

JOHN C. BLACK. EARLE W. GARD.

Coi 

